Category Archives: Weather

For the White Tank peaks, I’m lazy. I can get the key and drive. This morning I went up to check on the radio site on the east ridge where I have an ADS-B receiver and a railroad data receiver setup. The Windows PC there had apparently died a while back, the ADS-B link failed at the beginning of April, so it was time to fix things.

The cool thing about the White Tank road is it goes through the old Caterpillar proving grounds, where they pitted Caterpillar bulldozers against the mountain. And the White Tank road was part of the testing arena.

Verrado’s north end currently ends at the golf course; the tower road is the wide diagonal that heads northwest into the narrows up-canyon.

While Verrado continues to inch its way up the lower portions of the road, it’s unlikely it’ll ever get up this far. This what I call “the bowl”, where Caterpillar dozers not only moved millions of tons of rock back and forth for test and fun, but also cut the 20%-grade, ~0.6 mile long ramp that climbs north out of the bowl and then descends into the White Tank park boundaries.

On this fine day, there’s plenty of people walking the ramp. It’s windy as heck out, and the temperatures are in the mid-50’s, but the sun is warm.

Hauled out the dead PC. Am rebuilding it now to put back on the hill in the next week or two.

Ok, it took forever to get the blog running again, but today I’m playing with temperature and the dark sky. I don’t have a lick of math to back anything up (yet), but here’s what I’m seeing.

I have a cheap weather station (from Costco) .

This wx station comes with an “outdoor” temperature sensor.

I also have a near dead-flat white foamed roof on the house (seen in the background of the sensor above). I remember a long time ago one of my great mentors Bart telling me about the ability to use the cold of deep space to freeze water outside even when the air temperature is above freezing.

I’m here in the desert, and it’s fairly dry atmosphere. The ambient air temperature (as measured by the Davis wx station about 8 m away and 2 m higher)

is 47F (281K) right now, and the sensor sitting on the roof is showing 27.3F (270K). So 11K colder. Early this morning, when the outside air temp was 272K, the roof top sensor was showing about 264K. Hard freeze temperature. If I put a pan of water on the roof next to the sensor, it will be a disc of ice in the morning. Pretty neat!

So, how’s this work? I suspect that the hemisphere of sky that the sensor is exposed to above is pretty cold, significantly more than the 3K of the CMB but not anywhere near ambient air temperature. There’s a few palm trees that stick up into that hemisphere, but that’s a small portion of the overall scene, and palm trees probably don’t have a lot of heat contribution, though they do reflect the ground, which is currently over 273K. Since the atmosphere is fairly empty, there’s not a lot of heat energy between the roof and space – it’s a clear night. That lack of heat means that there’s probably not a lot of energy to illuminate my temperature sensor laying flat on the roof. So, for that hemisphere (at least), the heat energy available is pretty low.

Now on to the other hemisphere, the one below the sensor laying flat on the roof. Well, it’s all white foam and provides a pretty good insulation from the heat of the house and the ground and shrubberies, etc., nearby. The foam under the white coating is a closed cell yellow foam and probably has pretty poor heat conduction. Given that the foam also is low density, it probably doesn’t have much heat capacity so there’s not much contribution of heat energy from that lower hemisphere, and I imagine it cools rather quickly once the sun goes down.

So, here I’m measuring the temperature at the air layer about 1 cm above the roof, and well below the parapet wall around the roof at about 20 cm. It’s dead still tonight, so there’s little air mixing at the roof level. The Davis wx station uses their usual baffled temperature sensor and is pretty close to the other temperatures measured locally, though I suspect it’s biased a bit by being so close to the roof, and not on a nice piece of open land as per NOAA/NWS siting guidelines. I’ve got a homeowners’ association to deal with, doncha know…

Anyway, I will try to get some calculations going and see what I should be able to see. If I get very ambitious, I might even build a temperature sensor “tower” that can measure the temperature at a number of distances off the roof (from touching the roof to maybe 100 cm) and see what the gradient looks like.

This also explains why the truck windshield gets frost on it some night but not others. The windshield will chill due to seeing mostly the cold sky, and it will chill faster than the ambient air when there’s little air movement. If the temperature on the surface of the windshield gets below the dew point, then I should see water ice plate out on the windshield. This happened a few nights ago, and the ice was pretty resistant to defrosting.

On this hot yet fine July 4th, I decided to celebrate with a little wardriving and, while I was at it, visit a nice craft brewery or two.

First, I’d noticed that my percentage of the Wi-Fi AP database was at 54.9% (about 380k APs collected since February) could be improved and that the West Valley still has a lot of major arterials which haven’t been touched.

Today I decided to cover the rest of McDowell Rd from SR51 to the end in Verrado, and return via Indian School Rd. I discovered that McDowell actually ends just before Verrado at a (currently) dry wash, and there was no way to cross in the truck. But, nonetheless, I made it out to Verrado, drove through that artificial “America’s midwest (everyones’ home) town”, which reminded me of a Twilight Zone or two. The streets and houses are just like some backlot at Universal, and there’s no one on the streets. I mean no one. Sure, it was 103F out, but there’s plenty of trees and it was shady in spots, and there are 60-some-odd parks advertised there, but there was no one. Creepy. Did I also mention that Verrado is one of those neighborhood/communities that they built far in the middle of nowhere back in the last decade when commuting 30 miles to the city wasn’t considered an issue?

Anyway, you’d figure on the 4th of July, this “everyones’ home town” kind of place would be preparing for all sorts of festivities, with town fairs, barbecues, bunting, banners and flags. Instead, nothing. Even the downtown area was deserted. Wait, was that a tumbleweed blowing down the avenue?

On the way back east on Indian School, I realized that I wasn’t all that far from Peoria Artisan Brewery, and stopped in for a fresh pint. Jos poured up a Paul’s Pale Ale, and it was good. While I was sipping that, some thing in my mind reminded me of the fabled 8-Bit Brewing Company, to which I’d never been. I asked, and apparently it had opened at the beginning of May. Paid Jos for the beer and I was on my way to the world of pixelated animated characters.

After fording the mighty Agua Fria ditch, I turned into a generic industrial park and soon found a group of vehicles clustered in front of a non-descript industrial office suite. 8-Bit Brewery! Inside, Krystina was great, friendly, and very knowledgeable on their beers. Seems that she and her husband Ryan run the place, she manages the tap room, while Ryan cooks up the good stuff in back.

8-Bit is fun! It’s not a cozy tap room, just a high-ceiling’ed front of an otherwise industrial suite. However, to bring some warmth to the place, they have original paintings by a local artist who specializes in 8-bit art. Pretty cool. Famous characters back from the Mario days are immortalized here. And even cooler, they play only 8-bit music. While I didn’t hear any classics while trying a flight, Krystina says that there’s a local musician who takes popular songs and discretizes them, giving them that 1980’s 8-bit charm. She elaborated that he’d done this for a number of bands or artists; none interested me until she said that he’d discretized a Metallica song or two. Now, that I’ve got to hear.

The beers are tasty. I was able to sample all 6 beers currently on tap, and she also treated me to a white cocoa bean (which is one of the ingredients they use to make their White Mage white ale. Getting to try a white cocoa bean was ultra-cool. Like a peanut, except completely different. She also gave me and a number of other beer fans there a taste of the wort for their nice Black Mage stout, which was a fine stout. I’d never had a taste of wort, but it was sugary sweet, complex aroma, maybe a hint of anise, deep brown and cloudy. Got to thinking that it could be good as a glaze for roast pork!

Leaving Mario and Tanookis behind, I returned to my wardriving heading east on Indian School. Not much chance of rain today, but at least I collected another 10,000 or so APs.

In case you’re wondering where my webcams and weather station have gone, it appears that I’ve got a local problem with the power supply to the rooftop from the shack in the house.

Up on the roof is a GigE 8 port switch, two IP cameras, an ancient Linksys WRT54G router to provide Wi-Fi coverage around the property, a Raspberry Pi and SDR USB dongle running as an ADS-B receiver, and a UBNT 5 GHz bullet supplying a link to another Bullet over on the roof of the garage, to get my local network out to stuff in the garage. In addition, in the box on the roof, there’s a 12 vdc to 5 vdc converter to supply power to the Raspberry Pi. All told, this is only about 20-25 w of power consumption, which at the fused voltage of 12 vdc, should only be 2 A or so. So I can’t see the reason that a 10 A fuse is getting taken out.

I supply both 12 vdc and 48 vdc to the roof via a cable from the shack. There’s a 12 vdc to 48 vdc 150 w dc-dc converter in the shack to generate the 48 vdc. Both that and the raw 12 vdc are sourced from the 12 vdc deep-cycle battery in the shack, through a single 10 A fuse.

For some reason, yesterday I discovered the 10 A fuse had blown. Not good. I replaced the fuse and it appeared to start working again. However, I see this morning that the cameras and wx station were last heard from around 0641 local, so I suspect the fuse blew again.

Looks like this afternoon will include a visit to the roof to see what’s up.

Yes, it looks a lot like a golf cart, and to the uninspired, it smells and feels like one, but to the IRS and the DMV it’s a potentially street-legal electric-powered vehicle. Importantly, here in Arizona it’s a vehicle covered here under Arizona Title 28 Transportation, which describes the street-licensed vehicle parked in my driveway.

This particular one was a boondoggle purchase way back in 2009, due to some extremely generous federal tax credit legislation passed in 2008. Basically, the vehicle was a serious bargain. Runs off 48 VDC (eight 6-volt US Battery 250HC XC batteries), has a speed governor set to 25 MPH max, will easily run miles and miles on a single charge, has a AZ state license plate and registration, and has seat belts, headlights and turn signals.

In our neighborhood, which is gated with private streets, I can run the thing all day. Speed limit in the neighborhood is 20 MPH, with only 4 stop signs and over 2 miles of paved street. If I want to sneak out of the closed neighborhood, according to the statute (noted above) the vehicle is street-legal on roads with speed limits no greater than 35 MPH, and is permitted to cross streets with higher speed limits.

The NEV had been sitting in the boneyard for a few years and the batteries were in pretty poor condition. I know, I should know better on how to manage heavy expensive batteries, but the way the vehicle was built it is a bit challenging to water the batteries and they seem to, from day one, vent copious amounts of sulfuric acid vapor, causing all sorts of corrosion and erosion. Since each battery weighs about 40 kg, pulling all 8 batteries to properly inspect and water is a royal pain. However, I tore the vehicle apart again last month and determined to make all new cables, clean up all the corrosion, and get the thing running again.

For the most part, it’s all back together again and appears to work fine. I purchased 20′ of 2 gauge Excelene welding cable, 25 2-gauge solid copper tinned terminals, and an 8-ton handy-dandy hydraulic crimper tool with a bunch of dies (in case I want to go all hard-core with some 4/0 cables). This wealth of stuff set me back about $80. Add to this some silicone adhesive/sealant, adhesive-backed heat-shrink tubing, and boom! I’ve got new jumper cables to run from the motor controller to the battery bank.

This time I reorganized the batteries so that all the positive posts are completely accessible any time, so that I can more easily clean off the buildups of copper oxide/sulfide/sulfate residues that collect in mere days. This means that some jumpers are a little longer than in the original setup, but since they were using 4-gauge cable before I can stand the slightly greater lengths without sacrificing much at all. The maintenance headache reduction and reduced back strain to me are worth much more.

So, what do I do with this puppy? Well, not much, actually. When I first got it I did take it for some 5 to 10 mile drives, found my way (accidentally, really, truly) on to some golf course roads, went to the grocery store a few miles away (at night, no less), and even took it through the drive-through at Jack in the Box. Beyond that, none of my once-vaunted dreams to add wireless telemetry, GPS, audio, etc., ever transpired. However, I’m feeling the urge to finally get to these projects.

I am currently looking at using an Arduino as my real-time sensor controller, collecting battery voltage, maybe battery temperature, day/night light level, stuff like that. I might use Wi-Fi to form an RF link back to the house, possible as I put a 2.4 GHz Wi-Fi AP at 15′ atop the house on an 8 dBi omni antenna. In the Tahoe (which has a 5-6 dBi omni), I can actually get to one end of the neighborhood on the Wi-Fi link. However, I’m thinking more about using the 2m ham band and amateur packet radio, just in case I want to wander a bit further. I happen to have a little 5 watt 2m transceiver module, and a spare Kantronics KPC3Plus TNC, and a little GPS brick. The whole thing should pull less than 600 mW (50 mA average at 12 vdc), and transmit telemetry and position packets every minute. And, aprs.fi is already set up to display things like this, so there’s no backend work for me to do.

I’ve just started new employment, so this project, while exciting and interesting, will probably not get started for a while. But, while I’m continuing to procrastinate, I will also consider another project that I never got started on for this little NEV, and that was to add about 300 to 400 W of solar panel to the roof, so that I can trickle-charge the batteries at up to about 8 A (sadly, this is maybe C/35, so that’s why it’s a trickle charger). To add the panels I’ll need to find someone to weld up a sturdy bracket, and but at least in theory I could really be grid-free at least for short distances! And I’d be the talk of the neighborhood!!!

This morning I went out to get the car serviced. Wow, what a sky! Our quasi-benevolent alien overlords must be really busy today…

Appears that there’s significant upper-atmosphere water content as it makes for an impressive day of long-lingering aircraft contrails.

Some very discrete trails near the sun

I also tried out the new “Panorama” feature on my iPhone, to grab a pair of 180° views.

Centered on NNWcentered on SSE

Not all the clouds visible are from the contrails. With a little effort, it’s possible to separate some of the naturally occurring cirrus from the a/c contrails, but you can see places where the contrails have smeared out enough that telling the difference becomes more challenging.

It’s been over two weeks since I installed my ADS-B setup, and it’s been a real performer and seems to be very reliable. As I’ve pointed out, I’ve continued to tweak the setup, first with a better antenna, then by raising the antenna a bit, then with a cheap satellite preamp.

An important thing I still don’t know is the absolute amount of air traffic on any one day. ADS-B transmitters are only on a limited number of civil a/c, so it doesn’t see all the non-equipped a/c that might be flying on that particular day. I’ve never looked in any detail at commercial traffic repeatability, so I can’t say for sure if flight XYZ123 between airport A and airport B flies every day of the week. I don’t know if Monday is a busier flight day locally than is Tuesday. And with so many non-commercial airports within hearing range (KSDL, KDVT, KGEU, KFFZ, KCHD, KPAN, etc.) the number of small a/c equipped with ADS-B could change dramatically on any given day. KDVT has an especially large number of ADS-B-equipped a/c and they’re constantly flying loops around KDVT, so they provide a good number of position reports.

With all that said, when I saw the precipitous drop (34%) in location reports on the rainy day here on the 30th, I was concerned that my setup might have some issues that needed resolution. After doing a few checks, it appeared that things were nominal, so the next thing was to compare my station’s statistics with those of other stations near me. There aren’t any stations within 7 miles, but that was good enough to start as the rain was a southern-AZ-wide event, a good soaking, steady winter rain, which was over a very large area.

I took the best performing stations and a couple of typical stations for comparison. I also marked when I changed something in my setup to see if what I did actually mattered or if everyone else reflected some change that day which might indicate that my equipment changes had no particular effect.

Jon Adams ADS-B station vs other local ADS-B stations

The above graph (done in Excel) compares the JonAdams ADS-B receive site against two other solid performers (SN and DR) and two others down in the typical performance range (LY and PE). Raising the antenna (just noticed I drew it one day later than it should be) improved the performance from about 130k reports to about 150k reports. Adding the preamp was the real improvement, improving sensitivity and increasing the number of reports between 25 and 35%. I also noticed that my ultimate range improved as well. At least the preamp change to my station’s setup doesn’t correspond with significant changes in the other stations, so I’d say that the preamp was a big deal.

Another important thing, and why I started this article, was my concern over the rain having a specific deleterious effect on my station. But, it appears that the other high performers suffered very similar degradation. In my case, the drop was 34%. Comparing that to station SN, the drop there was also 34%. For station DR, the drop was 63%. For the other two typical stations, there was no particularly significant change in performance.

So, for now I will conclude that my ADS-B station has no unique problems not faced by other high performing stations. I remain interested in the cause of the drop, but have never had so much data at this particular frequency range that it’s going to take a little more Googling to figure out why and to what extent the rain should have an impact.

The above is a screenshot of the aggregated coverage over an approximate 120 hour period from last Saturday to now. The rings are spaced 50 km apart. As you can see, there are even a few a/c locations over 400 km away, which is incredible given that the house is in a bowl surrounded by hills or mountains in nearly all directions. For that one particular coverage radial SE into Sonora, that happens to be a very narrow clear shot (not including trees) from the house toward the horizon.

Initially, my setup included a simple discone antenna already sitting up on the roof, but in a day I had built the “QST Special” ADS-B antenna and my number of location messages went up from about 35k per day to over 130k per day.

After a few days of that, I raised the QST antenna by 4′ to get it above the parapet wall that surrounds the roof and the number of position reports went up by about 10-15% to about 150k. Next, I found in the garage a cheap (cheap being $5) cable satellite preamp and put that in line with the antenna. The position reports skyrocketed from about 150k to well over 200k per day. In fact, yesterday’s summary shows 240k+ position reports, and about 300 per second at peak times of the day. Here’s a chart which shows the changes in performance as a function of time and setup.

ADS-B Stats from 15 Jan to 2100 hours 30 Jan

As can be seen, the performance continues to improve as the setup is further tweaked. Today (30 Jan) looks to be a bad day for reception. It has been raining lightly (about 0.03″/hr) since before midnight. I expect that at the current rate the station will receive only about 160k position reports today, which will be about 2/3 of yesterday’s performance.

My assumption right now is that the connected rain drops on the antenna radome are causing significant loss of signal at the antenna radome (the ABS pipe it’s covered with). It’s also possible that the added attenuation of the signals as they travel through the rain clouds and falling rain is a factor. Not sure which is more significant. At 1090 MHz, light rain shouldn’t be a really significant issue, but perhaps the PiAware software decoder is running right on the edge of performance so even a dB or so of added loss could have an impact.

While the rain is great, I look forward to a few weeks of dry skies so that I can get a solid number on the performance as a function of day of week.